KR20220050222A - Electronically Operated Ramp Style Locking Differential with Lock Detection - Google Patents

Abstract

An electronic locking differential assembly according to the present disclosure includes a differential case, first and second side gears, a lock actuation mechanism, first and second tone wheels, first and second pickup sensors and a controller. The lock actuation mechanism includes a ramp plate that selectively moves between a locked state and an unlocked state. The first tone wheel has a first plurality of teeth formed on the differential case. The second tone wheel has a second plurality of teeth formed on the ramp plate. The first pickup sensor senses the position of the first plurality of teeth. The second pickup sensor senses the position of the second plurality of teeth. The controller determines whether the lock actuation mechanism is in the locked state or the unlocked state based on respective positions of the first and second plurality of teeth.

Description

Electronically Operated Ramp Style Locking Differential with Lock Detection

Cross-referencing of related applications

This application claims priority to U.S. Provisional Application No. 62/893,879, filed on August 30, 2019. The disclosure of the above application is incorporated herein by reference.

technical field

BACKGROUND The present disclosure relates generally to differential gear assemblies, and more particularly to an electronically actuated ramp style locking differential having a lock detection mechanism. it's about

A differential gear mechanism is provided in the axle assembly and may be used to transmit torque from driveshafts to a pair of output shafts. The drive shaft may drive the differential through the use of a bevel gear that meshes with a ring gear mounted on the housing of the differential. In automotive applications, the differential allows tires mounted on either end of the axle assembly to rotate at different speeds. This is important because as the vehicle turns, the outer tire travels through an arc of greater distance than the inner tire. Thus, the outer tire must rotate at a higher speed than the inner tire to compensate for the greater distance traveled. The differential includes a gear arrangement and a differential case that allow torque to be transmitted from the drive shaft to the output shafts while simultaneously allowing the output shafts to rotate at different speeds as needed. A gear arrangement may generally include a pair of side gears mounted for rotation with respective output shafts. A series of cross pins or pinion gear shafts are fixedly mounted to and for rotation with the differential case. A corresponding plurality of pinion gears are mounted for rotation with the pinion gear shafts and are in meshing relationship with both of the side gears.

Some differential gear mechanisms include traction modifying differentials such as those that provide a locking function. The locking differentials include some kind of locking mechanism for preventing rotation of one of the side gears with respect to the gear case, the engagement of the locking mechanism being initiated by some kind of actuator. By way of example only, the actuator may include a ball ramp mechanism in which rotation of a ramp plate is retarded with respect to the gear case, with an electromagnetic coil disposed adjacent the ramp plate. Initiates ramping in response to a transmitted signal. Other configurations are direct acting, wherein as the coil is energized, it is urged into a rod that is moved by movement of the armature so that it is moved to interlock with the side gear. clutch) is used. In this regard, many configurations are available. Examples of locking differentials of the type previously described herein are shown in US Pat. Nos. 6,083,134 and 6,551,209, both of which are assigned to the assignee of the present disclosure and are incorporated herein by reference.

The background description provided herein is for the purpose of generally presenting the context of the present disclosure. The presently nominated inventor's work - to the extent set forth in this Background section - as well as aspects of the description that would otherwise not otherwise qualify as prior art at the time of filing are expressly or implied prior to this disclosure. It is not recognized as a skill.

An electronic locking differential assembly according to the present disclosure includes a differential case, first and second side gears, a lock actuation mechanism, first and second tone wheels, first and second pickup sensors and a controller. The differential case defines first and second output shaft openings that are coaxially aligned along an axis of rotation of the differential case. The first and second side gears are rotatably mounted within the differential case. The first and second side gears are coaxially aligned along the axis of rotation of the differential case. The first side gear provides a first torque transmission connection with the first output shaft. The second side gear provides a second torque transmission connection with the second output shaft. The lock actuation mechanism includes a ramp plate that selectively moves between a locked state in which the side gears are fixed for simultaneous rotation and an unlocked state in which the side gears rotate relative to each other. The first tone wheel has a first plurality of teeth formed on the differential case. The second tone wheel has a second plurality of teeth formed on the ramp plate. The first pickup sensor senses the position of the first plurality of teeth. The second pickup sensor senses the position of the second plurality of teeth. The controller determines whether the lock actuation mechanism is in the locked state or the unlocked state based on respective positions of the first and second plurality of teeth.

In other features, the lock actuation mechanism further includes push rods respectively positioned in valleys of the ramp plate. The first plurality of teeth are integrally formed on the differential case. The second plurality of teeth are integrally formed on the ramp plate. A first pickup sensor is statically arranged proximate the differential case. A second pickup sensor is statically arranged proximate the lamp plate. The first and second side gears form a torque transmission device configured to transmit torque between the pinion gears and the first and second side gears to rotate the first and second side gears about an axis of rotation. intermeshed with pinion gears for The torque transmission device may also be configured to allow the first and second side gears to rotate at different rotational speeds relative to each other about the axis of rotation in the unlocked state.

An electronic locking differential assembly constructed in accordance with additional features of the present application includes a differential case, first and second side gears, a lock actuation mechanism, a first sensor, a second sensor and a controller. The differential case defines first and second output shaft openings that are coaxially aligned along an axis of rotation of the differential case. The differential case may include a first plurality of teeth formed around an outer surface of the differential case. The first and second side gears are rotatably mounted within the differential case. The first and second side gears are coaxially aligned along the axis of rotation of the differential case. The first side gear provides a first torque transmission connection with the first output shaft. The second side gear provides a second torque transmission connection with the second output shaft. The lock actuation mechanism includes a ramp plate that selectively moves between a locked state in which the side gears are fixed for simultaneous rotation and an unlocked state in which the side gears rotate relative to each other. The lamp plate includes a second plurality of teeth formed around an outer surface of the lamp plate. The first sensor senses the rotational position of the first plurality of teeth. The second sensor senses the rotational position of the second plurality of teeth. The controller determines whether the lock actuation mechanism is in the locked state or the unlocked state based on respective positions of the first and second plurality of teeth. The controller outputs a signal based on the decision.

In other features, the lock actuation mechanism further includes push rods respectively positioned in the valleys of the ramp plate. A first pickup sensor is statically arranged proximate the differential case. A second pickup sensor is statically arranged proximate the lamp plate. The first plurality of teeth are integrally formed on the differential case. The second plurality of teeth are integrally formed on the ramp plate. The first and second side gears form a torque transmission device configured to transmit torque between the pinion gears and the first and second side gears to rotate the first and second side gears about an axis of rotation. intermeshed with pinion gears for The torque transmission device may also be configured to allow the first and second side gears to rotate at different rotational speeds relative to each other about the axis of rotation in the unlocked state.

A method of determining whether an electronically locked differential assembly is in an unlocked or locked state comprises providing a differential case, the differential case having a first plurality of teeth formed around an outer surface of the differential case has - includes . A lamp plate is provided having a second plurality of teeth formed around an outer surface of the lamp plate. A first position of at least one tooth of the first plurality of teeth is sensed. A second position of at least one tooth of the second plurality of teeth is sensed. The controller determines whether the electronic locking differential assembly is in an unlocked or locked state based on the first and second positions. The controller outputs a signal based on the decision.

According to other features, sensing the first position includes sensing the first position from a first pickup sensor statically arranged proximate the differential case. Sensing the second position includes sensing the second position from a second pickup sensor that is statically arranged proximate the ramp plate. Outputting the signal from the controller includes outputting the signal to an instrument cluster that communicates the locked or unlocked state of the electronic locking differential assembly.

BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will be more fully understood from the detailed description and accompanying drawings.
1 is a schematic example of a simplified vehicle driveline;
2 is an exploded view of an exemplary electronic locking differential according to one prior art example;
3 is a perspective view of an electronic locking differential having a lock detection assembly constructed in accordance with an example of the present disclosure;
FIG. 4 is a detailed view of the lock detection assembly of FIG. 3 ;
5 is a plot illustrating that case sensor pulses for the case and lamp plate do not exhibit any phase lag for the electronically locked differential in the unlocked state.
6 is a plot illustrating that case sensor pulses for case and lamp plate exhibit phase lag for an electronic locking differential in a locked state.

Referring initially to FIG. 1 , an exemplary vehicle driveline is shown. In the example shown, the vehicle is front wheel drive, meaning that the primary motive power is connected to the front drive axle. An engine 106 , a transmission 107 , and a power transfer unit 108 are positioned at the front of the vehicle to directly transmit torque to the front left axle 100 and front right axle 101 . operatively connected. Wheels 102 , 103 receive torque via wheel hubs 115 and 116 to provide traction to the vehicle. Via mechanisms in the power transmission unit 108 , such as a hypoid gear and a pinion, the drive shaft 109 receives torque and transmits it to the rear of the vehicle. An optional all-wheel drive coupling 120 may be coupled to the drive shaft 109 , and the rear drive unit 110 may house an electronic locking differential 130 .

The rear electronic locking differential 130 may be operated in either an open mode or a locked mode. In the open mode, the left rear wheel 113 can rotate at a different speed than the right wheel 114 via the wheel hub 117 and the left rear axle 111 . Likewise, the right rear wheel 114 may rotate at a different speed than the left rear wheel 113 via the wheel hub 118 and the right rear axle 112 . In the locked mode, both the left and right rear wheels 113 , 114 receive the same torque as the left and right rear axles 111 , 112 are locked via internal components in the rear differential 130 . It will be appreciated that the driveline of FIG. 1 is an example and the principles may be used in rear wheel drive vehicles or in vehicles having more than one differential device.

Referring to Figure 2, an electronic locking differential 130 constructed in accordance with one prior art example is shown. The electronic locking differential 130 includes a differential gear case 213 having a pair of input pinion gears 217 . The pinion gears 217 include input gears of the differential gear set, and are meshed with a pair of side gears 219 and 221 . When the ring gear fixed to the right case 211 rotates, the pinion shaft 218 rotates with it. This in turn rotates the side gears 219 , 221 . The side gears 219 , 221 are a set of internal straight splines 223 , 225 in spline meshing with mating external splines on the respective left and right rear output axle shafts 111 , 112 , respectively. include those As the ring gear rotates, the rear axle shafts 111 and 112 rotate.

When the electronic locking differential 130 is operating in the open mode, during normal straight operation of the vehicle, no distinction is made between the left and right axles 111 , 112 or between the left and right side gears 219 , 221 . doesn't happen Accordingly, the pinion gears 217 do not rotate relative to the pinion shaft 218 . As a result, the left and right gear cases 212 , 211 , the pinion gears 217 , and the side gears 219 , 221 are all centered on the rotation axis A as if including a solid unit. rotate to However, when the vehicle rotates, or experiences turbulence that causes the rear wheels 113 , 114 to rotate at different rates, the pinion gears 217 may turn the pinion shaft to enable different side gear speeds for the pinion shaft rotation. It rotates around (218, 216). In some situations, it may be desirable to lock the left and right rear axles 111 , 112 so that they must rotate at the same rate. Thus, during locked mode, the side gear is locked to the housing such that it must rotate with the pinion shaft 218 . In the example shown in FIG. 2 , the left side gear 219 is locked through meshing engagement, which locks the pinion gears 217 relative to the side gear 219 , which also locks the side gear 221 . .

When the pinion shaft 218 rotates, the side gears 219 , 221 rotate, and accordingly, the rear axles 111 , 112 rotate. In the unlocked or open mode, each side gear 219 , 221 may rotate at a different speed than the other side gear, which may cause the side gears to rotate relative to the pinions 217 at different speed rates. Because. In the locked mode, the rocker gear 219 is coupled to the lock plate 210 . The right case 211 is coupled to the ring gear to rotate as the drive shaft pinion applies a rotational force. Since the rocker gear 219 is locked through the lock plate 210 to rotate with the differential case 213 at the same rate as the pinion shaft 218, the right side gear 221 is also locked from differential rotation, Likewise, it must rotate at the same rate as the rocker gear 219 . In this regard, the rear axles 111 , 112 rotate at the same rate via the locked differential 130 .

The actuation mechanism 233 includes electrical leads 259 that are coupled to an activation switch or other control means to energize the stator. The energized or unpowered state of the stator determines whether ramp plate 253 is ramped up or ramped down. When ramped up, the ramp plate 253 is rotated to push the peak areas on the ramp plate 253 against the push rods 247 , which pushes the push rods 247 towards the lock plate 210 . The lock plate 210 slides in the axial direction in a recess in the right case 211 . In the ramp down position, the ramp plate 253 is rotated so that the push rods can rest on the valleys of the ramp plate 253 . A wave spring may push the lock plate 210 , which in turn may push the push rods 247 into the valleys.

Referring now to FIGS. 3-6 , an electronic locking differential 300 having a lock condition detection assembly 310 constructed in accordance with the present disclosure will be described. Unless otherwise noted, electronic locking differential 300 may operate in locked and unlocked conditions as described above with respect to electronic locking differential 130 . Electronic locking differential 130 generally includes a differential case 320 and a lamp plate 322 . The differential case 320 defines first and second output shaft openings 324 , 326 that are coaxially aligned along an axis of rotation 328 of the differential case 320 . The first and second side gears (see also 219 and 221 of FIG. 2 ) are rotatably mounted in the differential case 320 , and the first and second side gears rotate the axis of rotation of the differential case 320 . aligned coaxially. The first side gear defines a first shaft opening configured to provide a first torque transmission connection with a first output shaft received within the first output shaft opening. The second side gear defines a second output shaft opening configured to provide a second torque transmission connection with a second output shaft received within the second output shaft opening. The lock actuation mechanism (see also 233 in FIG. 2 ) selectively moves between a locked state in which the side gears are fixed for simultaneous rotation and an unlocked state in which the side gears rotate relative to each other.

As will be appreciated from the discussion that follows, the lock condition detection assembly 310 uses a tone wheel and sensor pickup to decipher the position of the differential case 320 and lamp plate 322 relative to each other. In this regard, the unlocked differential will have the differential case 320 and the lamp plate 322 in phase. A locked differential will have the differential case 320 and lamp plate 322 out of phase. By knowing the state of the electronic locking differential 300 , the driver can more accurately predict driving and vehicle behaviors.

With particular reference to FIGS. 3 and 4 , the locked state detection assembly 310 will be further described. The differential case 320 includes a first tone wheel 330 . The ramp plate 322 includes a second tone wheel 332 . The first and second tone wheels 330 , 332 may include respective first and second plurality of teeth 340 , 342 . In some examples, the first plurality of teeth 340 may be integrally formed with the differential case 320 . Similarly, the second plurality of teeth 342 may be integrally formed with the ramp plate 322 . The first pickup sensor 350 is statically arranged proximate the first tone wheel 330 to sense the first plurality of teeth 340 . A second pickup sensor 352 is statically arranged proximate the second tone wheel 332 to sense a second plurality of teeth 342 .

As described above, the lamp style electronic locking differential operates by using an electromagnetic coil to provide a resistive torque to the lamp plate 322 . The ramp plate 322 then rotates independently of the differential case 320, allowing the locking mechanisms to engage internally. As the lamp plate 322 rotates relative to the differential case 320 , the first and second tone wheels 330 , 332 allow determination of the position of the differential case 320 and the lamp plate 322 respectively. can do. Electronic locking differential 300 requires either differential case 320 or ramp plate 322 rotation to occur to allow locking and unlocking to occur. The relative rotation of differential case 320 and lamp plate 322 may be sensed as voltage pulses to electronic control unit (ECU) 360 . ECU 360 calibrates how many relative rotations (pulses of in-phase or out-of-phase, i.e., out of phase) need to occur to determine whether differential assembly 300 is locked or unlocked from a previous state. It can store location algorithms that can be used to In some examples, ECU 360 can transmit a signal to instrument panel 364 or the vehicle that communicates to the driver that electronic locking differential assembly 300 is locked or unlocked in some examples. The present disclosure allows for static sensors on the axle, and no telemetry systems are needed within the axle.

Referring to FIG. 5 , the differential assembly 300 ( FIG. 3 ) is shown in an unlocked state. A first trace 366 represents pulses sensed by the differential case sensor 350 . The second trace 368 represents the pulses sensed by the ramp plate sensor 352 . In the unlocked state, there is no phase delay between the reference peak 370 of the differential case 320 and the corresponding reference peak 372 of the lamp plate 322 .

Referring to FIG. 6 , the differential assembly 300 ( FIG. 3 ) is shown in a locked state. The first trace 376 represents the pulses sensed by the differential case sensor 350 . A second trace 378 represents the pulses sensed by the ramp plate sensor 352 . In the locked state, there is a phase delay 390 between the reference peak 380 of the differential case 320 and the corresponding reference peak 382 of the lamp plate 322 .

As an example, ramp plate 322 may be configured to rotate about 18 degrees relative to differential case 320 from an unlocked state to a locked state. It is recognized that other degrees of rotation are contemplated between unlocking and locking within the scope of the present disclosure. Software logic in ECU 360 can determine, from signals from differential case sensor 350 and ramp plate sensor 352, in which position (locked or unlocked) electronic locking differential 300 is located. there is. In particular, the ECU 360 may store a tooth count of the first and second plurality of teeth 340 , 342 , the position of the differential assembly 300 and thus the locked state of the differential assembly 300 . It is possible to establish triggers to compare signals between sensors 350 and 352 to decrypt .

The foregoing description of examples has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but where applicable, although not specifically shown or described, are interchangeable and may be used in a selected example. It can also be changed in many ways. Such changes are not to be regarded as a departure from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

Claims (18)

An electronic locking differential assembly comprising:
a differential case, the differential case defining a first output shaft opening and a second output shaft opening coaxially aligned along an axis of rotation of the differential case;
a first side gear and a second side gear rotatably mounted within the differential case, the first side gear and the second side gear being coaxially aligned along the axis of rotation of the differential case, the first side gear the gear provides a first torque transmission connection with a first output shaft and the second side gear provides a second torque transmission connection with a second output shaft;
a ramp plate that selectively moves between a locked state in which the side gears are fixed for simultaneous rotation and an unlocked state in which the side gears rotate relative to each other lock actuation mechanism;
a first tone wheel having a first plurality of teeth formed on the differential case;
a second tone wheel having a second plurality of teeth formed on the ramp plate;
a first pickup sensor for sensing the positions of the first plurality of teeth;
a second pickup sensor for detecting positions of the second plurality of teeth; and
a controller for determining whether the lock actuation mechanism is in the locked state or the unlocked state based on the respective positions of the first plurality of teeth and the second plurality of teeth. , electronic locking differential assembly. According to claim 1,
and the lock actuation mechanism further comprises push rods respectively positioned in valleys of the ramp plate. According to claim 1,
and the first plurality of teeth are integrally formed on the differential case. According to claim 1,
and the second plurality of teeth are integrally formed on the ramp plate. The method of claim 1,
and the first pickup sensor is statically arranged proximate the differential case. 6. The method of claim 5,
and the second pickup sensor is statically arranged proximate the ramp plate. According to claim 1,
The first side gear and the second side gear may include pinion gears, the first side gear, and the second gear to rotate the first side gear and the second side gear about the rotation axis. intermeshing with the pinion gears to form a torque transfer arrangement configured to transfer torque between the side gears;
wherein the torque transfer device is also configured to allow the first side gear and the second side gear to rotate at different rotational speeds relative to each other about the axis of rotation in the unlocked state. . An electronic locking differential assembly comprising:
differential case - the differential case defines a first output shaft opening and a second output shaft opening that are coaxially aligned along an axis of rotation of the differential case, the differential case being about an outer surface of the differential case comprising a first plurality of teeth formed;
a first side gear and a second side gear rotatably mounted within the differential case, the first side gear and the second side gear being coaxially aligned along the axis of rotation of the differential case, the first side gear the gear provides a first torque transmission connection with a first output shaft and the second side gear provides a second torque transmission connection with a second output shaft;
a lock actuation mechanism comprising a ramp plate selectively moving between a locked state in which the side gears are fixed for simultaneous rotation and an unlocked state in which the side gears rotate relative to each other, wherein the ramp plate is a second plurality of teeth formed about the outer surface;
a first sensor for detecting a rotational position of the first plurality of teeth;
a second sensor for detecting the rotational positions of the second plurality of teeth; and
(i) determine whether the lock actuation mechanism is in the locked state or the unlocked state based on the respective positions of the first plurality of teeth and the second plurality of teeth; (ii) a controller outputting a signal based on the determination. 9. The method of claim 8,
and the lock actuation mechanism further comprises push rods respectively positioned in the valleys of the ramp plate. 9. The method of claim 8,
and the first pickup sensor is statically arranged proximate the differential case. 11. The method of claim 10,
and the second pickup sensor is statically arranged proximate the ramp plate. 9. The method of claim 8,
and the first plurality of teeth are integrally formed on the differential case. 9. The method of claim 8,
and the second plurality of teeth are integrally formed on the ramp plate. 9. The method of claim 8,
The first side gear and the second side gear are disposed between the pinion gears and the first side gear and the second side gear to rotate the first side gear and the second side gear about the rotation axis. intermeshed with the pinion gears to form a torque transmission device configured to transmit torque;
wherein the torque transfer device is also configured to allow the first side gear and the second side gear to rotate at different rotational speeds relative to each other about the axis of rotation in the unlocked state. . A method for determining whether an electronic locking differential assembly is in an unlocked or locked state, the method comprising:
providing a differential case, the differential case having a first plurality of teeth formed around an outer surface of the differential case;
providing a lamp plate, the lamp plate having a second plurality of teeth formed around an outer surface of the lamp plate;
sensing a first position of at least one tooth of the first plurality of teeth;
sensing a second position of at least one tooth of the second plurality of teeth;
determining, using a controller, whether the electronic locking differential assembly is in the unlocked state or the locked state based on the first position and the second position; and
outputting a signal from the controller based on the determination. 16. The method of claim 15,
wherein sensing the first position comprises sensing the first position from a first pickup sensor statically arranged proximate the differential case. 17. The method of claim 16,
wherein sensing the second position comprises sensing the second position from a second pickup sensor that is statically arranged proximate the ramp plate. 16. The method of claim 15,
wherein outputting the signal from the controller comprises outputting the signal conveying a locked or unlocked state to an instrument cluster.

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